Follow-up servomotor



May 15, 1951.

E. A. ROCKWELL 2,553,210

FOLLOW-UP SERVOMOTOR Original Filed June 29, 1943 4 Sheets-Sheet l INVENTOR ATTBQNEY May 1951 E; A. ROCKWELL 2,553,210

FOLLOW-UP SERVOMOTOR Original Fi led June 29, 1943 4 Sheets-Sheet 2 0 1 4 R 2, m Y. w mm N R E o w 9 V. T 2 e 9 m m m s 4 Y B E A ROCKWELL FOLLOW-UP SERVOMOTOR Patented May 15, 195T EdwardAe Rockwell, Cleveland, Ohio.

Original application June 29, 1943, Serial No.

492,745, now Patent No. 2,458,736, dated January 11, 194 9; Divided andithis application tober 28, 1944,, Serial N o. 560,868-

Claims.

My invention relates. particularly to aselfcontained power operated servo mechanism for controlling any device requiring. a relatively large amount of work to move the same. Also, it is especially adapted for use where small followthrough manual operating, input forces are ,required either by mechanical connections to the input or by other connections thereto, such for example as in the control of automotive vehicles, airplanes, steam engines, steering gears or locomotive reverse gears.

The present application is a division of my application upon Self-Contained Hydraulic Servo Mechanism,.Ser. No. 492,745, filed June 29, 1943, Patent No. 2,458,736, granted January 11, 1949'.

The object of my invention is particularly to provide a power-driven apparatus of the above character, for controlling any desired device. One of the objects is to provide a hydraulic power operated mechanism which is positive, certain and accurate in operation and which eliminates the disadvantages in previous valve-operating devices. A further object is to provide a power-driven valve-operating mechanism which operates effectively upon the principle of hydraulic pressure and volume displacement be tween the control mechanism and the output power members. Also, one-way check valves may be used in the high pressure lines leading to the valves to prevent reversibility in the output members. Furthermore, I have found it advantageous to utilize hydraulic pressures obtained from a manually operated master cylinder to maintain the coordination of travel between the input means and the output means. The results obtained are facilitated by the very slight travel of the valves, which assists in providing accurate increments of fluid for the control of the output means. This arrangement makes it feasible to provide an efficient hydraulic remote control whereby an accurate control may be readily obtained. Also, the master cylinders used are provided with suitable liquid compensation in order to maintain the phase relation between the control means and the output means. Still another object is to provide a remotely controlled power unit for controlling or operating mechanisms in which the power unit is a compact self-contained power unit.

In accordance with my invention, with the high hydraulic pressures available, cylinders of relatively small displacement can be used for controlling the output. These can be most conveniently mounted upon a box section housing and opposed to each other. Pistons are connected by push. rods to an output shaft trunnioned in the housing. The pivot of the crank shaft and output lever can be located at the same point that the lifting or tumbling shaft is located, and the whole unit mounted together. Monitor or travel control cylinders and pistons are mounted on either side below the output shaft, and. adapted to rest removably against a pin fixed on an extension of the crank attached to said shaft. Control master cylinders, in one form, are located below the monitor and are preferably bored in the same casting. The pistons are positively connected by links to an independent crank journaled in the housing and. having a control lever positioned on the outside of the box for con.- veni'ent attachment to the reach rod or other control. The interior of the box acts as a supply reservoir for the oil in which the gear pump and cylinder openings are submerged, so as to receive the return flow from the valves. The pump is mounted on a bracket extending down from the cover plate to which the air motor is also secured. The valves and pressure controller are also mounted. on the cover plate together with atube connection from the pump outlet, making a complete sub-assembly, so that these parts can be conveniently removed from the box. "External pipe connections aremade from each master-monitor outlet to the respective valve cylinder outlet. Air bleeders are. provided at the high point of these connections. Preferably check valves are placed in the lines leading from the pump and the controller to each of the valves to make the action irreversible. Lines also= connect with outlets from these valves to the respective power cylinders. Air bleeders are provided at the top of these cylinders to initially exclude all air and to allow for the initial cycling of the unit.

Further objects of my invention. will appear from the detailed description of the same herematter.

While my invention is capable. of. being. carried out in many diiferent ways for the purpose. of illustration I have shown only certain embodiments of my invention in the accompanying drawings, inwhich Fig. 1 is a diagrammatic side elevation of a locomotive reverse gear controlling mechanism operated in accordance with my invention;

Fig. 2 is a longitudinal vertical section of the valves and operating cylinders used therein;

Fig. 3 is an end elevation, partly in section, of the same;

3 Fig. 4 is a transverse section of the same taken on line 44 of Fig. 2;

Fig. is a vertical section of a check valve on the high pressure inlet to one of the modulator is attached a rod 1 passing through a projection 8 on a lever 2 and connected to a bifurcated hand operating lever 9 having a pivot I9 on said hand lever 2. A spring II around the rod 1 and located beneath the projection 8 normally keeps the catch 6 in engagement with any one of the notches of the rack 5. Attached to the lower end ofthe hand lever 2 there is a link or reach rod I2 which is pivoted to the upper end of a manually operated lever l3 havin a split end I4 adapted to be tightened in place by a screw I5 on a splined end I6 of a master cylinder operating shaft I1 which passes through a gland nut I8 having a packing I9 carried by a large assembly bushing 29 screw-threaded into a cylinder housing 2I having a supporting flange 22 for attaching the same by screws 23 to any desired part of the locomotive. The inner end of the master cylinder shaft I1 has thereon a crank 24 provided with a lateral crank pin 25 so as to be received in a recess 25 in a link 21 having pivots 28 and 29 connected to the master cylinder pistons 39 and 1-H, respectively, carried in master cylinders 32 and 33 in master cylinder blocks 34 and 35, respectively. The cylinder'bl-ocks 34 and 35 are attached to the side of the cylinder casing 2I in any desired manner. As the two master cylinders are constructed in the same way only one thereof will lbe'described. The master cylinder plunger 39 has around its periphery an annular chamber 36 which communicates by a port 31 with a pasageway '38 in the cylinder block 34 and which leads to a central chamber 39 in the cylinder casing 2|. The port 31 also serves for liquid compensation of the'cylinder 32 at the end of the path of the piston 49. The annular chamber 36 has a hole closed by a' plug 39a to enable the port 31 to be drilled. A rubber U-shaped seal 49 is provided on the piston 39 to the right of a flange 4! on the endof said piston. Also, the cylinder 32 has a screw cap 42.

The cylinders 32 and 33 have discharge ports 43 and 44 which lead, respectively, to travel control cylinders 45 and 46, closed by screw caps 41 and 48, and which have therein travel control plungers 49 and 59 having a recess 59a for a plunger return sprin 59b. These two travel control plungers have U-shaped rubberseals 5| and 52 adjacent to flange heads 53 and 54 thereon. The hydraulic liquid discharged under manual pressure from the chamber 32 and 33, respectively, after reaching the cylinders 45 and 46, is delivered by p ipes55 and 56 to inlet ports 51 and 58 in valve cylinder heads 59 and 69, respectively, having air bleeder screws BI and 62. The cylinderheads 59 and 69 are located, respectively, on valve cylinders 63 and 64 joined together with a packing65 and fastened in any desired way on the top of a cover plate 65a on top of the cylinder housing 2|. The cylinder heads 59 and 69, furthermore, have within the same, respectively, I

chambers 66 and 61 having therein plungers 68 and 69 provided with U-shaped seals 19 and H. The said plungers 68 and 69, also, have thereon heads 12 and 13 which provide valve seats 14 and 15 for cooperating with tubular valves 16 and 11 provided with annular valve elements 18 and 19 cooperating with the valve seats 14 and 15. The Valve 14, 18 acts as a discharge valve communicating with a discharge port 89 in the valve cylinder housing 2| through the cover plate 65a on the housing 2|. Similarly the valve 15, 19 communicates with a similar port BI communicating with said chamber 39. The tubular valve members 16 and 11 are constructed just alike and only one thereof will be described in detail accordingly. The tubular valve 16 has an annular seal 82 and a peripheral valve-balancing chamber 83 communicating with an inlet port 84 connected to a high presure hydraulic liquid inlet pipe 85 provided with a check valve 86. A' branch high pressure hydraulic liquid in let pipe 81, having a check valve 81a, leads to a similar inlet 86 on the valve cylinder 64. The said tubular valve 16, furthermore, has a conical inlet valve 89 cooperating with a valve seat 99 on the inside of the valve cylinder 63. Also, said tubular valve 19 has a plurality of radial aper-.- tures 9I connecting with a cylindrical chamber 92 in the tubular valve 16 and with a chamber 93 on the outside of the tubular valve 16 which leads to a port 94 for supplying the modulated high pressure liquid which passes through the valve 99, 99 to a pipe 95 and thence to an inlet port 96 on a power cylinder 91. Similarly, the valve cylinder 64 has a delivery outlet aperture 98 for the liquid delivered by the valve 11 which is thence conveyed by a pipe 99 to an inlet open-v ing I99 on'a power cylinder IN. The tubular valve 19, furthermore, has an annular seal I92 within a sleeve I93. Also, between the inner ends of the tubular valves 16 and 11, which are individually self-lapping, there is a coil spring I94 for pressing the conical valves 89 against their seats 99. The spring I94 is located in a chamber I95 which communicates by a port I96 in the sleeve I93 and a passageway I91 with the chamber 39. The passageway I91 serves as a breather opening. An internal spring I98 between pistons I99 and H9, located within the tubular valves 16 and .11, serves, by means of piston rods III and H2 on said pistons I99 and H9 and attached to the heads 12 and 13 respectively, to unseat the valves 14 and 15 normally. Also, it will be noted that the pistons I99 and H9 and the attached plungerheads 12 and 13 serve to balance the release valves 19, 18 and 15, 19. Rubber seals H3 and H4 are located on the piston rods I I I and H2.

The power cylinders 91 and I9I are provided with screw caps H5 and H6. Pistons II1 and'II8 and piston rods I I9 and I29 are connected to a pivot I2I on a'lever arm I 22; which is in the form of a yoke carrying said pivot I2I The lever arm I 22, furthermore, is carried upon a splined shaft I 24 having a locking screw I25. The shaft I24 is carried within bushings I26 and I21 in the cylinder housing 2! and a packing I28 is located adjacent to the bushing-I21'and held in place by a gland nut I29. Furthermore, the lever I22 hasfa downwardlly directed bifurcated end I39 provided with a cross pin I3I which 'is located between the inner ends of the two travel control plungers 49 and 59. 1 e e @n the outer end of the shaft I 24 there 'isa lever 'a'rm' I32 fastened in place with a washer I33 and a nut I34. The lower end of the lever arm I32 is pivoted to a yoke I35 of a locomotive reverse gear such as is shown, for example, in Fig. 5, and for operating any desired type of loconiotive reverse gear, such as is shown in Marks, Mechanical Engineers Handbook, first edition, 1916, pages 975 and 971, published by McGraw- Hill Book Co. Inc., New York.

The: high pressure liquid supplied by the pipe 85 to the tubular valve 16, 11' is delivered from a'gear pufnp I 36 of any desired type, mounted on a bracket I'36a on the cover plate 8011 so as to receive liquid from the chamber as by the usual inlet opening, which is driven by a shaft I31, which shaft in turn is driven by an air vane or other motor I38, as shown in Fig. 1. However, it may be an electric motor, as shown in my Patent No 2,292,546, upon Snap Action Apparatus. The motor I 38, which is fastened to the cover plate 6511, may be driven by compressed air received through an opening I39 from a pipe I40 whichleads to a fitting I4I on the top of a pressure accumulator casing I42, also fastened to the cover plate 65a, having a compressed air inlet opening I43. The supply of compressed air to the pipe I40 is controlled by a valve plunger I44 having a conical valve member I45 cooperating with a valve seat I46 on the interior of the fitting MI. The valve I45, I46 is normally un sea-ted. For this purpose, the valve plunger I44 has a longitudinal passageway to receive a bolt I41, on one end of which there is a head I48 adjacent to an annular spacing plunger I49 to hold in place a rubber seal I50. The'other end of thebolt I41 passes through a seal I5I and a spacing member I52 and thence through a washer I5Zd and a split retainer ring I53 and a washer I53a in the fitting I4I against the lower face of which there is provided a coil spring I54 held in place by a washer I55 and a nut I56. The sup-' ply of compressed air from the inlet I43 to the port I40 is adapted to be out off automatically when there is a sufiicient accumulation of pressure in the hydraulic liquid in the system so as to interrupt the operation of the gear pump I36. For this purpose, the pipe 85 has a branch pipe I51 which leads by a fitting I58 to a passageway I59 in a base block I80 to which the accumulator casing I42 is secured. The passageway I59 leads to a plunger chamber I6I having a plunger I62 therein provided with an annular seal- I63.- The plunger I52 operates against a screw head I64 which is located over a snap action screw I65 where it is held in place by a nut I66 so as to support a dished plate I81 having a series of openings I68 in a flange I69 thereon which supports a plurality of coil springs I around tubes I1I within the holes I68. The

tubes I'II receive through the same lockingbolts I12 which hold the casing I42 against the block I50 by being screw-threaded into said blockand having their ends provided with nuts I13 and I14 so as, also, to hold the fitting M1 on the casing I42. At their upper ends the coil springs I10 are retained in place by washers I on the rods I12 and adjacent to said washers I15, nuts I16 and I11 hold in place a spider I18. The said spider I18 has a central aperture I19 adjacent to which there are a plurality of pivoted arms I80, carried on pivots I81 and pressed inwardly by springs I82. The lower ends of the arms I80 have pivoted therein rollers I83 to bear on the outside of a tubular member I84 having secured thereto a peripheral flange I85 located on a snap action block I88. Within the tubular member I84 there is a spring retainer sleeve I81 carrying within the same a coil. spring I08 located on the outside of asleeve I89. The sleeve I89 is 10- cated on a snap action rod I89a which at this end has a head I90 adjacent to a washer I9I. The rod I8-9a is arranged to slide within the snap action block I86 and beneath said block the rod I891: carries a spring retainer sleeve I92 within which there isa coil spring I93 located over a sleeve I94 on the rod I89a. Adjacent to the sleeve I94, at its lower end,- there is provided a washer I95 and the rod I89a is arranged to hold the washer I95 in place by the rod I89a being fastened by a tongue I96 and a groove I91 and a cross pin I98 to the snap action screw I85. This snap action is shown in detail in iny U. S; Patent No.- 2,292,546, above referred to.

In the operation of my invention shown in Figs. 1 to 4, when the hand lever 2 is in the middle portion, as shown in Fig. 1, the locomotive is at rest. If it is desired to drive the locoi'ndtive forwardly it is moved towards the right in said figure and if it is to be driven rearwardly it is moved towards the left, By the movement of said lever 2 to the right the link or reach iod I2 is moved to the left together with the lever I3. This moves the crank 24 to the right, in Fig.- 2, thereby moving the master cylinder piston 3| to the right and simultaneously delivering the liquid under manual pressure by the pipe 58 to the interior of the plunger cylinder- 61 while at the same time withdrawing the liquid from the plunger cylinder 86 to the pipe'55. Accordingly, the valve 15, 19 will become seated, thereby seating the pressure liquid inlet on the" tubular valve member 11 and admitting the pressure liquid past this inlet, whence it is delivered by the pipe 99 to the interior of the power cylinder I0'I so as to move the piston I I8 therein to the right, in 2, while simultaneously moving the piston H1 in the other power cylinder 91 to the right iiisaid figure. The discharge from the power cylinder I-0I is accomplished by the unseating of the valve- 15, 19 and the discharge of the liquid by the' port 8'I to the interior of the casing 21. This movement of the power pistons I I1 and II8' resul'- ts in moving the crank I22 to the right, in Fig. 2, and thereby the shaft I24 so asto move to the left the arm I30 with the travel controlpistons 49' and 58 as well as the arm I32. The movement of the arm I32 transmits the motion to the link I35 and thence to the reverse gear of the locomotive so as to shift the radius rod, in the usual way in operating the locomotive reverse gear. At the same time that the power pistons H1 and H8 are moved, as above referred to, the shaft I24, by means of. the arm I30, will. move the travel control pistons 49 and 50 so that the travel of the rod I35 in either directionwill be coordinated to the travel of the master pistons 30 and 3I and, therefore, also to the travel of the manual lever 2 in either direction. It will be understood that the move ment or the hand lever 2 towards the left, in Fig. 1, will bring about the reverse series of opera-- tions of the parts referred to, in order to drive the locomotive rearwardlly. In the operation of the said parts the high pressure liquid is provided. to supply the ports 84 and 88 in the valve cylinders, by the compressedair which enters the. inlet port I43 past the valve I44, I45 and thence to the air motor I38 which drives the pump gear shaft I31 so as to deliver the high pressure liquid through the pipe 85 for supply to the valve inlet ports84 and 88. This pressure supply is maintained at a given level of pressureby the pressure accumulator I42 in which the piston I62 accumulates the pressurereceived from the gear pump by the yielding of the coil springs I70 to such a point that when the desired pressure tobe maintained is reached the snap action apparatus in the said accumulator causes the interrupted'surface or annular flange I85 to suddenly pass by the rollers I83 so that to and operable by said Connection and said cas-' the end of the sleeve I84 contacts with the plug I55 to'close the valve I45, I46, and keep'the same closed until the release of the pressure on the base of the piston I62 causes the springs I10 to move the interrupted surface or annular ring I85. back below the rollers I83 by a sudden snap action. The snap action produces a positive and quick opening or closing of the valve I45, I46, thus aiding and maintaining at all times the desired pressure in the supply of high pressure liquid; r

While I have described my invention above in detail I wish it to be understood that many changes may be made'therein without departing from the spirt of the same.

I' claim:

1. In combination, a casing, a source of fluid pressure, work performing pistons, a valve mechanism for controlling the supply of fluid pressure thereto, cylinders for said pistons mounted 1 on opposite'sides of the casing, the pistons having-aconnection to each other within the casing, and master cylinders in the casing, having hydraulicconnections to the valve mechanism, 101" operating the valve mechanism, said casing having therein a work performing element connected to and operable by said connection, and said casing having a make-up passageway in the cylinder wall provided with a port leading from said casing having therein a work performing element connected to and operable by said connection and said casing having a make-up passagewayin' the cylinder'wall provided with a port leading from each of said master cylinders, manual control means for said master cylinder pistons and valve mechanism, travel control pistons. havinghydraulic connections respectively to the master cylinder pistons and work performing pistons, adapted to coordinate the movement of the control means and work performing pistons, and cylinders for the travel control pistons mounted on said casing.

w "3.-'In combination, a casing, a source of fluid pressure, work performing pistons, a valve mechanism, for controlling the supply of fluid pressure thereto, cylinders for said pistons mounted on opposite sides of the casing, the pistons having a connection to each other within the casing, master cylinders in the casing, having hydraulic connections to the valve mechanism, for operating the valve mechanism, said casing having therein a work performing element connected ing having a make-up passageway in the cylinder wall provided'with a port leading from each of said mastercylinders, and an output lever having'a pivot on the casing.

4. In combination, a casing, a source of fluid pressure, work performing pistons, a valve mechanism for controlling the supply of fluid pressure thereto, cylinders for said pistons mounted on opposite sides of the casing, the pistonshaving a connection to each other within the easing, master cylinders in the casing, having hydraulic connections to the valve mechanism oppositely located travel cylinders having hydraulic connections to said cylinders respectively, for operating the valve mechanism, said casing having therein a work performing element connected to and operable by said connection and said casing having a make-up passageway in the cylinder wall provided with a port leading from each of said master cylinders, and an output lever having a pivot on the casing, the master cylinders andtravel control cylinders being located below said pivot.

5. In combination, a casing, a source of fluid pressure, work performing pistons, a valve mech-' anism'for controlling the supply of fluid pressure thereto, cylinders for said pistons mounted on opposite sides of the casing, the pistons having a connection in and passing through the casing, oppositely located master cylinders, having hydraulic connections to the valve mechanism, for operating the valve mechanism, oppo-, sitely located travel cylinders having hydraulic connections to said cylinders respectively, an output lever having a pivot on the casing, and a lever on said pivot leading to said piston connection, the master cylinders and travel control cylinders being located below said pivot, each of two opposite sides of said casing having a master cylinder and a travel control cylinder in a single block. 7 1 EDWARD A. ROCKWELL.-

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 692,868 Lemp Feb. 11, 1902 752,491 Warren Feb. 16, 1904 897,907 Lang Sept. 8, 1908 1,062,561 Williams et al. May 20, 1913 1,147,436 Ragonnet July 20, 1915 1,299,284 Baader Apr. 1, 1919 2,061,120 Vorech Nov. 17, 1936 2,109,114 Kerr Feb. 22, 1938 2,236,467 Clench Mar. 25, 1941 2,239,893 .Jackman Apr. 29, 1941 2,252,660 Kulikoff 1 Aug. 12, 1941 2,261,444 Neubert Nov. 4, 1941 2,286,661 Warner June 16, 1942 2,365,247 Carlton Dec. 19, 1944 2,458,736 Rockwell Jan. 11, 1949 FOREIGN PATENTS Number Country Date 374,583 Great Britain June 16, 1932 710,182 France June 1,1931

702,983 Germany Feb. 25, 1941 

